Trace amounts of natural and synthetic estrogens released into the environment by wastewater-treatment plants are known to cause reproductive abnormalities in fish. Researchers have now found an even more dramatic consequence of exposure to the synthetic estrogen used in birth control pills—the near extinction of a fish population.
Women taking birth control pills excrete the synthetic estrogen 17alpha-ethynylestradiol along with natural estrogens. Male fish exposed to estrogens at concentrations of only a few parts per trillion (ppt) can become intersexual, displaying male and female tissues in their gonads (SN: 3/10/07, p. 152).
"A big question remained